基于有限元的地图综合算法及其在LBS中的应用

发布时间：2019-04-10 07:33

【摘要】：地图综合作为地图学的核心和难点问题之一，从20世纪60年代以来始终受到学界和业界的重视和关注。由于数字环境下的地图综合及其复杂且求解难度大，使其成为现代地图学中最具挑战性和创新性的研究领域。在地理要素中，，线要素占了80%以上，而线要素化简算法是地图综合领域中研究和应用的最核心的内容。线要素化简的目的是对大量冗余数据点进行压缩以提取必要的数据点，且保持线要素的主要特征，使存储量最少。本文利用弹性力学中弹性体受到外力作用发生形变，撤销外力恢复原形的思想，将有限元方法应用到线要素化简中，提出一种基于有限元的线要素化简算法，并将该算法应用到基于位置的服务(Location Based Service, LBS)中。本文的主要研究工作和创新点包括如下方面： (1)提出一种基于有限元的线要素化简算法，该算法利用有限元方法对线要素进行化简，达到基于路线的化简，而不是基于点的化简。目前，基于有限元对地图综合的研究大多在位移算子方面，而对化简算子的研究较少。本文以GPS轨迹为研究对象，按照地图缩放的比例尺进行分级的线状轨迹化简，提高地图的可视性和显示效率。 (2)该算法不仅实现对图形特征的化简，同时还实现对语义特征聚合分析。利用GPS轨迹的特殊性，包含时间这项语义特征，即轨迹上每个点都包含一个时间信息，在对图形特征进行化简的同时，可对时间进行聚合，完成对语义特征的聚合。将图形特征化简和语义特征聚合在一起同时进行，改变了传统化简算法中将图形特征和语义特征分离开来的缺憾，使化简后的可读性更强。 (3)基于本文提出的算法，从几何观点出发，选取三个指标对化简算法进行评价。从实验结果可以看出本文提出的化简算法具有较好的稳定性。 (4)结合该化简算法，实现具有实时地图综合功能的空间定位服务系统，其中重点实现移动目标历史轨迹的动态化简服务、移动目标历史轨迹时间特征的语义分析服务、移动目标的聚合服务，并在宁波边防船舶监控系统中得到实际应用。功能是从数据库中检索出船舶的历史定位坐标，在地图上根据客户端分辨率、比例尺大小等条件，分级的描绘历史轨迹或化简轨迹。本文提出的化简算法从全局出发，综合考虑图形特征和语义特征，达到基于路线的化简且具有较高的稳定性，并保留了更多的语义信息，为基于位置的服务提供更加丰富的信息。
[Abstract]:As one of the core and difficult problems in cartography, map synthesis has been paid more and more attention by academia and industry since 1960's. Because map synthesis in digital environment is complicated and difficult to solve, it has become the most challenging and innovative research field in modern cartography. Among the geographical elements, the line elements account for more than 80%, and the line feature reduction algorithm is the core of the research and application in the field of map synthesis. The purpose of line feature reduction is to compress a large number of redundant data points to extract the necessary data points, and to preserve the main features of line features so as to minimize the storage capacity. In this paper, based on the idea that the elastic body is deformed by the external force, the finite element method is applied to the simplification of the linear elements, and a line element simplification algorithm based on the finite element method is proposed, in which the elastic body is deformed by the external force and the external force is removed from the original shape. The algorithm is applied to location-based service (Location Based Service, LBS). The main research work and innovations of this paper include the following aspects: (1) A line feature reduction algorithm based on finite element method is proposed, which uses the finite element method to simplify the line elements to achieve route-based simplification. Rather than a point-based simplification. At present, the research of map synthesis based on finite element is mostly in the field of displacement operator, but the research on simplification operator is less. In this paper, the GPS trajectory is taken as the research object, and the hierarchical linear trajectory reduction is carried out according to the scale of the map to improve the visibility and display efficiency of the map. (2) the algorithm not only simplifies the graphic features, but also realizes the aggregation analysis of semantic features. Taking advantage of the particularity of the GPS trajectory, it contains the semantic feature of time, that is, each point on the track contains a time information. While simplifying the graph features, we can aggregate the time and complete the aggregation of the semantic features. The simplification of graphic features and semantic features are aggregated together at the same time, which changes the shortcomings of separating graphic features from semantic features in the traditional simplification algorithm, and makes the simplified features more readable. (3) based on the algorithm proposed in this paper, three indexes are selected to evaluate the simplified algorithm from the point of view of geometry. The experimental results show that the simplification algorithm proposed in this paper has good stability. (4) based on the simplified algorithm, the spatial positioning service system with real-time map synthesis function is realized, in which the dynamic simplification service of moving target historical track and the semantic analysis service of historical track time characteristic of moving target are realized. Mobile target aggregation service, and in Ningbo frontier ship monitoring system has been applied in practice. The function is to retrieve the historical positioning coordinates of the ship from the database, and describe the historical track or the simplified track on the map according to the conditions of the client resolution, scale size and so on. The algorithm proposed in this paper considers the graph features and semantic features comprehensively from the global point of view, and achieves route-based simplification with high stability, and preserves more semantic information. Provides more information for location-based services.
【学位授予单位】：浙江理工大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：P283.1

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